At the end of the story I still feel good about LINQ to SQL when it comes to smaller applications with less complexity. Entity Framework is capable of handling large enterprise applications and will have more power in v2 (in .NET 4.0). So if you are targeting your application for multiple databases the L2S is not the right choice for you.

My vote is for ADO.NET Entity Framework. You will enjoy with the conceptual model and Astoria.